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  • 101.
    Mellin, Pelle
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Kantarelis, Efthymios
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    CFD approach to investigate fast pyrolysis by pre-heated steam, in a fluidized bed reactor2012Conference paper (Other academic)
  • 102.
    Mellin, Pelle
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Kantarelis, Efthymios
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Computational fluid dynamics modeling of biomass fast pyrolysis in a fluidized bed reactor, using a comprehensive chemistry scheme2014In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 117, no Part A, p. 704-715Article in journal (Refereed)
    Abstract [en]

    The CFD modeling for fast pyrolysis has previously focused on the major pyrolysis products; liquid, charand gas. This paper introduces a new approach to biomass pyrolysis; integrating a complex scheme of reactions including formation of such components as levoglucosan. The 3-D simulation takes into account the complex breakdown of each biomass subcomponent, the fluid dynamics of the process as well as the heat and momentum transfer of three Eulerian phases.

    The pyrolysis products include reference species that reflects the composition of the bio oil, gas fraction and char fraction. A number of reactions are in addition applied to account for the thermal cracking of tar compounds and the final compositions are compared to experimental yields. The results show that the predicted pyrolysis products reflect the experimental yields satisfactorily, apart from the water content which is under predicted. Most importantly though, the approach is computationally feasible and it should be useful for future work.

  • 103.
    Mellin, Pelle
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Kantarelis, Efthymios
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Processing of biomass to Hydrocarbons – using a new catalytic steam pyrolysis route2014Conference paper (Other academic)
    Abstract [en]

    Obtaining renewable transportation fuel has been identified as one of the main challenges for a sustainable society. Catalytic pyrolysis followed by hydrotreatment has been demonstrated as one possible route for producing transportation fuels. Using steam in this process could have a number of benefits as given by our research effort. For this paper, we will show that a catalyst together with steam prolongs the activity of the catalyst by preventing coking. This means that both steam and catalyst mutually benefits the deoxygenation. The presented mass and energy balance shows that up to 40% of the calorific value of biomass remains in the deoxygenated oil, on dry basis. This is in contrast to the mass yield, which for the same case was 25%; meaning that the oil is of significantly higher quality with a high content of hydrocarbons. In addition, CFD studies have shown steam is able to redistribute the heat flux and provide more uniform operating conditions compared to for example nitrogen. In conclusion, this route using steam shows promise for displacing fossil transportation fuels, by upgrading of the liquid in existing refineries or next-generation bio refineries. In additional support of this, we have published a number of papers describing conventional fast pyrolysis using steam, CFD modeling for further understanding and experimental work using a combination of steam and firstly a bimetallic catalyst (Ni, V) then a metal modified HZSM5 catalyst (Ni, V, Zeolite, Binder). This paper connects all these individual studies and provides further understanding of the role of steam and the role of steam in combination with a catalyst, in the fast pyrolysis process.

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  • 104.
    Mellin, Pelle
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Kantarelis, Efthymios
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Zhou, Chunguang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Simulation of Bed Dynamics and Primary Products from Fast Pyrolysis of Biomass: Steam Compared to Nitrogen as a Fluidizing Agent2014In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 53, no 30, p. 12129-12142Article in journal (Refereed)
    Abstract [en]

    Fast pyrolysis of biomass, using steam as a fluidizing agent, provides several benefits. In this paper, an unsteady multiphase computational fluid dynamics (CFD) model coupled with a comprehensive kinetic scheme for primary pyrolysis is used to obtain the formation rates of primary products and compare the profiles when operating with steam and nitrogen. The model only considers the physical effects of the fluidizing gas at the moment, although a literature review indicates the existence of various chemical and surface-interacting effects. At stabilized pyrolysis reaction rates, the product yields were compared to data found in the literature, which indicated similar yields; this supports the correct implementation of the kinetic model. However, the difference in overall rate and composition is very small when steam is compared to nitrogen. The simultaneous simulation of bed dynamics indicate a shifted formation rate of primary products toward the lower part of the fluidized bed, with an increase in solid vapor contact time and better temperature distribution as a result. More specifically, total heat flux to the biomass increased by 1396 in the lowest part of the reactor. In addition, more heat from the sand is carried through the gas phase when using steam: an increase by 9% in the overall reactor (25% in the lowest part), as indicated by the results. Finally, since no substantial differences in overall product formation rate and composition were found, the considerable effect of steam found in experiments and the literature is mainly (not exclusively) attributed to the chemical and surface-interacting mechanisms. Because of the complex nature of secondary pyrolysis in this process, a comprehensive gas-phase kinetic model is needed to investigate the effects of steam further. Coupling of both is difficult, because of computational constraints, as the present model already is very demanding. The obtained profiles of formation rate of primary products can however be used as an input to another model specifically made for studying homogeneous secondary pyrolysis reactions.

  • 105.
    Mellin, Pelle
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Wei, Wenjing
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Salman, H.
    Hultgren, A.
    Wang, C.
    Biomass availability in Sweden for use in blast furnaces: International Conference on Applied Energy, ICAE20142014In: Energy Procedia: International Conference on Applied Energy, ICAE2014, Elsevier, 2014, p. 1352-1355Conference paper (Refereed)
    Abstract [en]

    Based on the type of BF operated in Sweden, the pulverized coal (PC) has primarily been considered replaceable. If replacing the PC, a reduction of 1.25 Mton CO2 annually is possible, which would require approximately 4 TWh charcoal (0.46 Mton) or 7.14 TWh of dry raw biomass. This amount of biomass is substantial and availability is the main concern discussed in this paper. Uncertainty of the future biomass supply makes predictions beyond 2030 difficult. However, the predictions used in this work indicate that there is an unused potential, which could cover the need of all PCI in Sweden. Other aspects could potentially limit the proportion of PCI replaced by biomass, which should be further investigated.

  • 106.
    Mellin, Pelle
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Wu, Yueshi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Kantarelis, Efthymios
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    CFD Modelling of Heat Supply in Fluidized Bed Fast Pyrolysis of Biomass2014In: Proceedings of the 10th International Conference on Computational Fluid Dynamics in the Oil & Gas, Metallurgical and Process Industries (CFD 2014), 2014Conference paper (Other academic)
    Abstract [en]

    This paper investigates the heat supply to the fast pyrolysis process, by addition of oxygen in the fluidizing gas. Since the technology will be further developed, a solution for the heat supply in a large-scale reactor must be conceived, which is one option to achieve the primary target: to operate with as little extra heat as possible.

    Corrections for the granular bed material and the biomass particles are implemented in the simulation. User Defined Functions (UDF) is extensively used to describe interactions of heat and momentum between the phases and a chemistry model is employed to describe the chemical reactions after pyrolysis.

    The results are preliminary; however, the oxygen clearly reacts to provide heat. Primarily the secondary tar reacts and a loss of about 30% organic liquid yield is the result in this simulation, at an equivalence ratio of 0.026.

    If heat only can be recovered from the bed zone, through the bed material, then a higher equivalence ratio than what was investigated in this paper would be needed.

    If heat can be recovered from the whole reactor then a slight injection of oxygen would result in an autothermal system; which means the necessary heat to generate and pre-heat steam would be available.

    Temperature instability in the freeboard prevented investigation of higher equivalence ratios, which should be pursued in further work.

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  • 107.
    Mellin, Pelle
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yu, Xi
    Comprehensive secondary pyrolysis in fluidized-bed fast pyrolysis of biomass, a fluid dynamics based modelling effort2015In: 12TH INTERNATIONAL CONFERENCE ON COMBUSTION & ENERGY UTILISATION / [ed] Jiang, X; Joyce, M; Xia, D, 2015, Vol. 66, p. 281-284Conference paper (Refereed)
    Abstract [en]

    Homogenous secondary pyrolysis is category of reactions following the primary pyrolysis and presumed important for fast pyrolysis. For the comprehensive chemistry and fluid dynamics, a probability density functional (PDF) approach is used; with a kinetic scheme comprising 134 species and 4169 reactions being implemented. With aid of acceleration techniques, most importantly Dimension Reduction, Chemistry Agglomeration and In-situ Tabulation (ISAT), a solution within reasonable time was obtained. More work is required; however, a solution for levoglucosan (C6H10O5) being fed through the inlet with fluidizing gas at 500 degrees C, has been obtained. 88.6 % of the levoglucosan remained non-decomposed, and 19 different decomposition product species were found above 0.01 % by weight. A homogenous secondary pyrolysis scheme proposed can thus be implemented in a CFD environment and acceleration techniques can speed-up the calculation for application in engineering settings.

  • 108.
    Mellin, Pelle
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yu, Xi
    Aston University, European Bioenergy Research Institute (EBRI), Birmingham B4 7ET, U.K..
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Influence of Reaction Atmosphere (H2O, N2, H2, CO2, CO) on Fluidized-Bed Fast Pyrolysis of Biomass Using Detailed Tar Vapor Chemistry in Computational Fluid Dynamics2015In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 54, no 33, p. 8344-8355Article in journal (Refereed)
    Abstract [en]

    Secondary pyrolysis in fluidized bed fast pyrolysis of biomass is the focus of this work. A novel computational fluid dynamics (CFD) model coupled with a comprehensive chemistry scheme (134 species and 4169 reactions, in CHEMKIN format) has been developed to investigate this complex phenomenon. Previous results from a transient three-dimensional model of primary pyrolysis were used for the source terms of primary products in this model. A parametric study of reaction atmospheres (H2O, N2, H2, CO2, CO) has been performed. For the N2 and H2O atmosphere, results of the model compared favorably to experimentally obtained yields after the temperature was adjusted to a value higher than that used in experiments. One notable deviation versus experiments is pyrolytic water yield and yield of higher hydrocarbons. The model suggests a not overly strong impact of the reaction atmosphere. However, both chemical and physical effects were observed. Most notably, effects could be seen on the yield of various compounds, temperature profile throughout the reactor system, residence time, radical concentration, and turbulent intensity. At the investigated temperature (873 K), turbulent intensity appeared to have the strongest influence on liquid yield. With the aid of acceleration techniques, most importantly dimension reduction, chemistry agglomeration, and in-situ tabulation, a converged solution could be obtained within a reasonable time (∼30 h). As such, a new potentially useful method has been suggested for numerical analysis of fast pyrolysis.

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  • 109.
    Mellin, Pelle
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Zhang, Qinglin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Kantarelis, Efthymios
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    An Euler–Euler approach to modeling biomass fast pyrolysis in fluidized-bed reactors – Focusing on the gas phase2013In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 58, no 1-2, p. 344-353Article in journal (Refereed)
    Abstract [en]

    A developed 3D Euler–Euler CFD model, with an integrated pyrolysis model, is proposed as a way of predicting vapor phase dynamics and product distributions in the fluidized bed process for biomass fast pyrolysis. The main interest in this work is the gases resulting from the pyrolysis mixed with the fluidizing gas. We propose therefore a simple rendering of the solid material while directing attention to the vapor phase. At the same time the required computational resources for reaching stabilized conditions in the reactor are reduced. Temperature profile, velocity profile and pyrolysis products are predicted and globally verified by a series of parallel cases, which are compared to experimental measurements and known trends of liquid, solid and gas yields. The comparison of experimental measurements and model predictions satisfy the accuracy of the model and on a quantitative basis, the product yields agree with commonly known trends of bio oil versus temperature and residence time.

  • 110.
    Mellin, Pelle
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Zhang, Qinglin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Kantarelis, Efthymios
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Zhou, Chunguang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Accuracy and Potential Use of a Developed CFD-pyrolysis Model for Simulating Lab-scale Bio Oil Production2012In: The 20th EU BC&E Online Proceedings 2012, 2012, p. 953-959Conference paper (Other academic)
    Abstract [en]

    The paper describes development of a CFD¬pyrolysis model using an Eularian-Eularian framework with an implemented pyrolysis reaction model. The CFD¬pyrolysis model is used to simulate the bubbling fluidized bed reactor integrated in a new experimental fast pyrolysis process for bio oil production. The model is compared to experiments in aspect of outlet gas composition, temperature and bed height. Tar behavior and yield of bio oil are illustrated and a parametric study investigates impact of flow rate and temperature on bio oil yield. The results show a tolerable fit compared to measurements and reasonable tendencies in the parametric study.

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    2DO.8.2_20th_2012
  • 111. Mörtberg, M.
    et al.
    Blasiak, W.
    Gupta, Ashwani K.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Dynamics of a fuel jet injected into high temperature and oxygen deficient cross-flow2005In: Collect. Tech. Pap. Int. Energ. Convers. Eng. Conf., 2005, p. 121-140Conference paper (Refereed)
    Abstract [en]

    The combustion characteristics of propane gas jet injected into a cross-flow of high temperature have been examined using a specially designed experimental high temperature air combustion facility. The combustion air could be either normal or reduced oxygen concentration air. The composition and temperature of the combustion air flow can be controlled and varied in order to simulate phenomena that occur in high temperature air combustion conditions. The momentum flux ratio between the fuel jet and the combustion air flow was kept constant to provide similarity between the different experimental cases and to understand the role of fuel jet property on mixing and combustion. Information has been obtained on the global flame features, flowfield and OH, CH and C2 intermediate species during combustion. The results have also been obtained under isothermal case to show the direct role of combustion on the fluid dynamics. The results showed a strong dependence of the oxygen content and air preheats temperature on the fluid dynamics and the spatial distribution of intermediate species from within the flames. The noise emission results showed significantly reduced noise levels under high temperature air combustion conditions. The results showed significant role of the combustion air temperature and oxygen content on mixing, gas jet expansion and combustion. It was found that the mixing is hampered under high temperature air combustion conditions as compared to the normal air case. This resulted in zones of higher axial strain over prolonged distances as compared to the normal temperature air case. The fuel jet penetration into the surrounding combustion air is significantly enhanced under combustion conditions and depends on combustion air properties.

  • 112.
    Mörtberg, Magnus
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Study of gas fuel jet burning in low oxygen content and high temperature oxidizer2005Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    During the past decade, new advanced combustion systems that share the same basic concept of using a substantially diluted and high-temperature oxidizer in the reaction volume have gained a great deal of interest regarding their application in industrial and power systems. These novel combustion technologies have proved to offer significant benefits compared to traditional combustion techniques. These benefits include reductions in pollutant emissions and energy consumption, as well as a higher and more uniformly distributed heat flux. This entails the potential to, for example, reduce the size of equipment in industrial units or increase production rates while fuel consumption and the subsequent CO2 emissions are decreased or maintained at the same level.

    Although the development of these new combustion technologies has occurred fairly recently, it has gained worldwide recognition. During the past few years the technique has been used commercially with several different types of burners. Despite its widespread use, the basic understanding of the chemical-physical phenomena involved is limited, and a better understanding of the combustion phenomena is required for more effective utilization of the technology.

    The objectives of this work have been to obtain fuel-jet characteristics in combustion under high-temperature, low-oxygen conditions and to develop some theoretical considerations of the phenomena. The effect of the preheat temperature of the combustion air, combustion stoichiometry and the fuel-jet calorific value on flame behavior was investigated. Temperature and heat-flux distribution were also studied using a semi-industrial test furnace to see if similar flame features would be found for the small- and large-scale experiments.

    Particle Image Velocimetry (PIV) was used for the first time to obtain information on the flow dynamics of a fuel jet injected into a crossflow of oxidizer at either a normal temperature or a very high temperature. Light emission spectroscopy was used to collect information on time-averaged radical distributions in the combustion jet.

    Jet turbulence, time-averaged velocity distribution, fuel-jet mixing, the distribution of radicals such as CH, OH and C2, and flame photographs were investigated. The results showed delayed mixing and combustion under high-temperature low-oxygen-concentration conditions. The combustion air preheat temperature and oxygen concentration were found to have a significant effect on the burning fuel-jet behavior. The results of the semi-industrial-scale tests also showed the features of even flame temperature and heat flux.

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    FULLTEXT01
  • 113.
    Mörtberg, Magnus
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasaik, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Gupta, A.K.
    Experimental Investigation of Flow Phenomena of a Single Fuel Jet in Cross-Flow during Highly Preheated Air Combustion Conditions2007In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 129, no 2, p. 556-564Article in journal (Refereed)
    Abstract [en]

    Particle image velocimetry and a spectroscopy technique has been used to obtain information on the flow dynamics and flame thermal signatures of a fuel jet injected into a cross-flow of normal temperature and very high-temperature combustion air Flame fluctuations were obtained using a high-speed camera and then performing fast Fourier transform on the signal. High-temperature air combustion has been demonstrated to provide significant energy savings, higher heat flux, and reduction of pollution and equipment size of industrial furnaces. The dynamics of flow associated with high temperature combustion air conditions (for mean velocity, axial strain rate and vorticity) has been obtained in two-dimensional using propane and methane as the fuels. The data have been compared with normal temperature combustion air case, including the nonburning case. A specially designed experimental test furnace facility was used to provide well-controlled conditions and allowed air preheats to 1100 degrees C using regenerative burners. Four different experimental cases have been examined. The momentum flux ratio between the burning and nonburning conditions was kept constant to provide comparison between cases. The results provide the role of high-temperature combustion air on the dynamics of the flow, turbulence, and mixing under nonburning and combustion conditions. The data provide the direct role of combustion on flow dynamics, turbulence, and flame fluctuations. High-temperature combustion air at low-oxygen concentration showed larger flame volume with less fluctuation than normal or high-temperature normal air cases. High-temperature combustion air technology prolongs mixing in the combustion zone to enhance the flame volume, reduce flame fluctuations, and to provide uniform flow and thermal characteristics. This information assists in model validation and model development for new applications and technology development using high-temperature air combustion principles.

  • 114.
    Mörtberg, Magnus
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Gupta, A.K.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Lateral Fuel Jet Injection into High Temperature Oxygen Deficient ConditionsManuscript (Other academic)
  • 115.
    Narayanan, Krishnamurthy
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Wang, W.
    KTH.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Ekman, T.
    Flameless oxyfuel combustion: technology, modeling and benefits in use2006In: Revue de métallurgie (Imprimé), ISSN 0035-1563, E-ISSN 1156-3141, Vol. 103, no 5, p. 210-217Article in journal (Refereed)
    Abstract [en]

    Flameless oxyfuel combustion used in industrial furnaces gives a uniform temperature and heat flux distribution along with high available heat. NOx emissions can be maintained at extremely low levels, meeting the most demanding environmental regulations. Since 2003 the experimental results from flameless oxyfuel technology have been proven in industrial installations such as reheating and annealing furnaces as well as in ladle preheating stations.

  • 116.
    Niska, John
    et al.
    Swerea MEFOS, Heating and Metalworking Department.
    Grip, Carl-Erik
    Luleå University of Technology, Division of Energy Science.
    Mellin, Pelle
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Investigating Potential Problems and Solutions of Renewable Fuel Use in Steel Reheating Furnaces2013Conference paper (Other academic)
    Abstract [en]

    Implementing renewable fuels in steel reheating furnaces can reduce carbon dioxide emissions from fossil fuels, so the steel industry is interested in finding the optimal method of implementation. The relatively low cost of solid biofuels from forest products make them an attractive candidate, but there is a risk of reaction between pellets ash and furnace brick. Therefore a test was conducted with wood pellets ash on a furnace brick to test the sensitivity to pellets ash. One problem is the formation of a glassy phase due to the interaction of furnace refractories with pellets ash. The risk for the formation of a glassy phase depends on the composition of the refractory, composition of the ash and the furnace conditions, for example, a glassy phase was found to form on a chamotte refractory furnace brick when a pellets ash and the brick were heated to 1200°C.

    One method to analyze the risk for volatile and low melting point compounds from solid biofuels is to use a tertiary phase diagram to divide various components in the ash. Oxides and compounds rich in the alkali metals (Na and K) tend to form volatile compounds. These alkali metal oxides together with silica can give low melting point phases for compositions near the bottom of this diagram. Ash compositions near the top of the diagram which are rich in CaO and MgO tend to have higher melting points. The wood pellets ash investigated was analysed and found to contain a large percentage of Ca, Si and Mg, expressed as CaO (44.4%), SiO2 (14.6%) and MgO (10.1%) and relatively modest amounts of the alkali metals Na and K expressed as Na2O (3.5%) and K2O (6.2%). This mostly stem wood pellets ash could give concern with the formation of a glassy phase, so biofuels with more twigs, leaves and bark with a higher concentration of alkali metals could give even greater concerns. Therefore alternatives like gasification should be considered.

    Gasification of solid biofuels is one way to avoid ash-forming compounds in reheating furnaces. A survey was performed to evaluate different gasification technologies, as well as existing applications of syngas in other high-temperature industries.

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    Manuscript
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    Presentation
  • 117.
    Nurdiawati, A.
    et al.
    Japan.
    Zaini, Ilman Nuran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Aziz, M.
    Japan.
    Efficient hydrogen production from algae and its conversion to methylcyclohexane2018In: Chemical Engineering Transactions, ISSN 1974-9791, E-ISSN 2283-9216, Vol. 70, p. 1507-1512Article in journal (Refereed)
    Abstract [en]

    Herein, the supercritical water gasification (SCWG) of microalgae combined with syngas chemical looping (SCL) for H2 production and storage employing liquid organic H2 carrier (LOHC) system have been proposed and analysed in terms of energy efficiency. Microalgae are converted to syngas in the SCWG module and then introduced into the SCL module to produce high-purity of H2 and a separated CO2 stream. H2 storage is achieved via the hydrogenation reaction using toluene to produce methylcyclohexane (MCH). The heat released from the exothermic hydrogenation reaction is exploited to generate steam for sustaining the SCWG reaction. Simulations were performed using Aspen Plus™ considering the feed concentration and SCWG temperature as the system variables. The simulation results show that the SCWG reaction can be energetically self-sustained using the proposed configuration. Based on the process modelling and calculations, the proposed integrated system exhibited of approximately 13.3 %, 42.5 %, and 55.8 % for power generation, H2 production, and total energy efficiency.

  • 118.
    Pawel, Donaj
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Swiderski, Artur
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Kantarelis, E.
    Zabaniotou, A.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Reforming study of electric cable shredder from car residues into high-purity synthetic gas: Paper # (08-A-32-AWMA-IT3)2008In: Air and Waste Management Association - 27th Annual International Conference on Thermal Treatment Technologies 2008, 2008, p. 709-716Conference paper (Refereed)
    Abstract [en]

    Car industry and also another producer consume spend huge amount of electric cables. After end of life equipment this is a source of nonferrous metals and electric cable shredders. This paper presents experiment study on high quality synthetic gas produce from plastic cables isolation shredders take advance of high temperature gasification. Experimental results of laboratory scale batch type gasification reactor are presented. Small amount of samples was inserted to process agent like mixture of oxygen (1% vol.) with nitrogen and just in to pure steam. Tests were repeated in different temperatures up to 1323K. Base on this experiments mass balance, composition and heating value of gas was calculate. Moreover tars composition was investigate. All the cases with gasification agents and different temperatures were repeated with different duration time and mass loss ratio were draw. High temperature of the process gives strong impact on hydrogen production and tar decomposition. Pure steam gasification significantly improves gas heating value and reduce tar amount in gas.

  • 119.
    Persson, Henry
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Duman, Isa
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Wang, Shule
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Pettersson, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Catalytic pyrolysis over transition metal-modified zeolites: a comparative study between catalyst activity and deactivation2019In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 138, p. 54-61Article in journal (Refereed)
    Abstract [en]

    The utilization of metal-doped zeolites in catalytic pyrolysis of biomass is a well-known approach to promote the formation of certain compounds. One major technical issue of using zeolites in biomass pyrolysis processes is their rapid deactivation due to coke formation. However, little is known about how metal-doping influences the characteristics of coking, such as coking rate and its composition.

    In this study, four different materials were experimentally evaluated based on their catalytic activity and coking characteristics: HZSM-5, Fe/ZSM-5, Ni/ZSM-5 and FeNi/ZSM-5. The materials were prepared and characterized followed by screening in a bench-scale setup for in-situ catalytic pyrolysis. The mass balance and composition of pyrolysis products including catalyst coke were analyzed.

    It was found that metal-doping increases the concentration of aromatic hydrocarbons in the liquid product from 59.0 to 82.8 % of GC/MS peak area, especially monoaromatic hydrocarbons (MAHs) and naphthalenes. Fe mainly promotes MAHs whereas Ni additionally promotes naphthalenes. FeNi/ZSM-5 enhances the production of both compound groups as well as further reducing the total acid number (TAN). Regarding the catalyst coke, metal-doped catalysts present an increased concentration of aromatic hydrocarbons in terms of MAHs, naphthalenes and polyaromatic hydrocarbons. For each catalyst, the chemical composition of catalyst coke reflects the catalyst’s activity seen in vapor upgrading. A reaction pathway based on the observed catalyst activities of metal-doped ZSM-5 and HZSM-5 is proposed.

    The results also show that metal-doping of catalysts increases the formation of catalyst coke, mainly due to a higher concentration of strong acid sites. Also, the rate of coking is dependent on the strength of acid sites, where the strength correlates with the severity of coking. The coke yield was seen to increase from 3.5 wt% in the case of HZSM-5 to maximum 7.2 wt% over Fe/ZSM-5. However, the metal-doping of catalysts reduces the temperature of catalyst regeneration and catalyzes the oxidation of coke. Overall, this work presents a comparative study between catalyst activity and deactivation during thermochemical conversion of biomass.

  • 120.
    Ponce Valle, Maria Gabriela
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Combustion characteristics of steam-exploded biomass pellets2011Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Currently pelletized woody biomass is widely used as a fuel in thermal applications toaccelerate the global transition to renewable energy. Fuel upgrade is one of the key factorsto improve energy conversion processes. Woody biomass can be fractionated into its mainconstituents by steam explosion. Steam-exploded biomass exhibits enhanced heating valueand improves pellet durability. Moreover, there is a significant deviation in thermochemicalbehavior of steam exploded (steam-treated) biomass with respect to the raw material duringpyrolysis.

    This thesis work concerned combustion characteristics of steam-exploded salix. The steamtreatedmaterial was pelletized and combusted under 21% of oxygen with varying thereactor temperature from 500 to 900°C to study the influence of both surrounding andpretreatment conditions during combustion process. The impact of different pretreatmentseverity factors (Ro) on burning behavior was evaluated: mild (205°C-6min, Ro=3.87),intermediate (205°C-12min, Ro=4.17) and severe (228°C-12min, Ro=4.84). Heterogeneousand homogenous ignition mechanisms were observed, which were dependent on the reactortemperature. The ignition time and devolatilization duration were observed independent onpretreatment severity near 900°C, and slightly influenced near 500°C. Enhanceddevolatilization rate was detected with the increment of Ro from 3.87 to 4.17, whilst themost severe pretreatment conditions (Ro=4.84) weakened biomass reactivity duringdevolatilization. Finally, char reactivity was lowered as a result of the increment ofpretreatment severity.

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    masters_MGabriela Ponce
  • 121.
    Ponzio, Anna
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Thermally homogenous gasification of biomass/coal/waste for medium or high calorific value syngas production2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

     Today’s problems with emissions of green house gases, land filling of waste and depletion of the oil reserves calls for new energy systems based on alternative fuels like biomass and waste. Gasification is an attractive technology for the use of such solid fuels. Conventional gasification, in the vast majority of cases, uses in-reactor heat release from combustion of part of the feedstock, possibly coupled with a limited preheating of the agent, to obtain the necessary temperatures in the gasifier bed. During recent years, a new gasification technology, using highly preheated gasification agents (> 1273 K), has been developed. The extra heat brought into the process by the high temperature agent reduces the amount of feedstock that has to be oxidized to supply the necessary heat and the use of highly preheated agents has previously proven to have several positive effects on the fuel gas quality.In difference to the previous work on gasification with highly preheated agents, this thesis primarily focuses on the fundamental aspects namely, mass conversion, heating and ignition. It starts by considering single fuel particles or thin beds of fuel particles inserted into highly preheated agents. Mass conversion, heating and ignition are reported in function of the temperature and oxygen concentration of the agent and formulas for the prediction of ignition time and ignition mechanism are developed. The perspective is then widened to include the whole gasifier bed. Simulations of fixed bed batch gasification using highly preheated agents are performed with a mathematical model and used to study how the high agent temperature influences the mass conversion, devolatilisation front rate and the temperature distribution in the fixed fuel bed. Further, the gas quality and gasification efficiency are studied by means of large scale experiment. Ultimately, a thermodynamic analysis of the whole autothermal gasification system, including both a regenerative preheating system and the gasifier, is made.The particle study reports results from experiments with wood and coal and agents consisting of mixtures of nitrogen and oxygen in various proportions. It is shown that an increase in agent temperature from 873 K to 1273 K make the conversion process faster, mostly due to an early onset of the devolatilisation (fast drying) but also due to an increased devolatilisation rate (at least in the case of wood). The time to ignition also decreases significantly, particularly so between 873 and 1073 K. Further, it is shown that the higher the agent temperature, the more pronounced was also the tendency of the coal particles to heat significantly faster in oxygen diluted conditions (5,10 and 21% oxygen) than in inert (0% oxygen) or oxygen rich conditions (30, 50, 80 and 100% oxygen). An increase in agent temperature is also shown to reduce the dependency of the process on the oxygen concentration, at least in diluted conditions (5-21% oxygen). The results also indicate that for coal an increase in the oxygen concentration, specifically in the region above the atmospheric concentration, leads to a decreased dependency on the agent temperature. It is finally shown in the experiments with agent temperatures of 1073 and 1273 K that a flame is promptly formed even in very low concentrations of oxygen.The gasifier study reports results from simulation of batch air gasification and experiments in both batch and continuous up-draft fixed bed gasifier with wood and waste derived fuel and air and mixtures of air and steam. It is shown that the conversion process is faster the higher the air temperature. In particular somewhere between air temperatures of 623 K and 803 K the process behaviour changes. In fact, the devolatilisation rate is significantly increased in this region while it increases less sharply with air temperature below and above this temperature window. The temperature distribution in the bed shows less sharp gradients at high temperature (> 803 K) than at low temperatures (< 623 K). It is also showed experimentally and in fairly large scale that the use of highly preheated air for the gasification of biomass and waste derived fuels can produce - in continuous mode – relatively high yields of product syngas with relatively high fractions of combustible gases and probably also low content of tar. The efficiency of the gasification under these conditions, even when the extra heat input in the preheated agent is considered in the computation of the gasification efficiency, is shown to be comparable to that of conventional gasification techniques. The results also shows that with the use of steam in the agent, the content of hydrogen can be further increased with respect to gasification with only preheated air.In base of the results of the particle study and the gasifier study it is shown that a there exists two regimes of operation in function of the agent temperature, separated by the minimum agent temperature to guarantee spontaneous ignition regardless of the particle temperature. The value of this temperature depend on material properties and the kinetics of the reaction, thus also on the oxygen concentration. When agent temperatures below the minimum agent temperature to guarantee spontaneous ignition regardless of the particle temperature are used, the drying and devolatilisation are mainly controlled by the heat released by reactions. The heating of the fuel particles and their devolatilisation are relatively slow and the devolatilisation rate is highly oxygen dependent. In a fixed bed, the devolatilisation front rate is low and the bed is characterised by significant temperature gradients.When the agent temperature is higher than the minimum agent temperature to guarantee spontaneous ignition regardless of the particle temperature, the drying and devolatilisation are mainly controlled by the convective heat transfer from the preheated agent and the released volatiles ignite very fast even in diluted conditions. This results in very efficient heat transfer to the fuel particles. In the fixed fuel bed the process is characterized by a high devolatilisation front rate. Thus, the temperature gradients in the bed are significantly reduced and the gasification can be said to be thermally homogeneous. Thanks to high rates of heat transfer and mass conversion, the heating value of the dry produced syngas is high with high concentrations of combustible species. The ignition of the volatiles and the high temperatures all along the bed presumably contributes to the reduction of the tar content even in up-draft configurations. The high temperatures also allows for operation with reduced air – to – fuel ratios which further increased the value of the produced gas (thanks to less dilution by nitrogen).The system study presents a concept for an autothermal system including both preheating and gasification. Results from a thermodynamic analysis of such a system are reported. Autothermal operation of a thermally homogeneous gasifier is possible only in a twin component system in which the gasifier is coupled to a preheating system able to reach preheating temperatures well above the minimum agent temperature to guarantee spontaneous ignition regardless of the particle temperature. It is shown that to reach certain temperature levels of the gasification air, heat exchange between product gas and air is not enough and the preheating system has to improve the temperatures involved, for example by burning part of the produced gas in a regenerative preheater. Further, it is shown that in comparison to gasifier without such a system for additional preheating, the autothermal Thermally Homogeneous Gasification system has the ability to significantly improve the gas quality (in terms of heating value of the dry gas) without losing energy- or exergy efficiency to an appreciable extent.

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  • 122.
    Ponzio, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Kalisz, Sylwester
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzmierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Effect of operating conditions on tar and gas composition in high temperature air/steam gasification (HTAG) of plastic containing waste2006In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 87, no 3, p. 223-233Article in journal (Refereed)
    Abstract [en]

    In this work, the high temperature air/steam gasification (HTAG) technique has been tested for a fuel in pellet form made from waste material of woody and plastic origin. The feedstock was gasified in an updraft fixed bed reactor by mixtures of air and steam (102 Nm(3)/h, 4% to 82% steam) preheated to 1400 degrees C, a temperature well above the fluid temperature of the feedstock. The produced gas was analyzed with respect to composition, including a detailed characterization of the tar. Lower heating values up to 9.5 MJ/Nm(3) and gas yields as high as 3.4 Nm(3)/kg were reported, indicating the process to be highly efficient for waste-to-energy applications. The composition of the tars, suggested extensive cracking as a result of the high temperatures of the outgoing gas.

  • 123.
    Ponzio, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Senthoorselvan, Sivalingam
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Eriksson, O.
    Nitrogen release during thermochemical conversion of single coal pellets in highly preheated mixtures of oxygen and nitrogen2009In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 88, no 6, p. 1127-1134Article in journal (Refereed)
    Abstract [en]

    In this investigation, single coal particles (pellets) were combusted in highly preheated oxidants (8731273 K) with oxygen concentrations ranging from 0% to 100%, using a small scale' batch reactor. In base of the experimental results, the influence of oxygen concentration and oxidizer temperature on total mass conversion, the release of fuel nitrogen and the fraction of fuel nitrogen that is oxidized to NOx, is discussed. For oxygen concentration 5-21%, the rate of the thermochemical conversion was shown to be almost independent oxygen concentration when oxidant temperatures of 1073-1273 K were used. The opposite was true for an oxidant temperature of 873 K. Thus there appears to be an oxidant temperature above which devolatilisation is controlled by convective heat transfer rather than reaction. Further it was shown that the release of fuel nitrogen was promoted by an increased oxygen concentration (from 5% to 21% at 1273 K) and an increase of oxidant temperature (from 1073 K to 1273 K at 21% oxygen). An estimate of the devolatilisation of nitrogen from the measured pellet temperature indicated that the devolatilisation of nitrogen is significantly delayed with respect to other components. In fact, during the very initial part of the thermochemical conversion, most released nitrogen appeared to follow the route via char rather than via devolatilisation. Favorable conditions for No reduction thanks to a prompt devolatilisation contemporarily to a release of fuel nitrogen via the char route was believed to be one of the explanation for the evidenced low ratios between NOx emissions and fuel nitrogen released, particularly in the beginning of the experiment. The fact that the amount of released fuel nitrogen that is oxidized to NOx was shown to decrease with increasing oxidant temperatures from 1073 K to 1273 K supports this interpretation, though a higher temperature of the oxidant creates higher devolatilisation rates.

  • 124.
    Ponzio, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Senthoorselvan, Sivalingam
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Eriksson, Ola
    Combustion of coal in high temperature oxygen diluted and oxygen enriched conditions2006In: A and WM, Annual International Conference on Incineration and Thermal Treatment Technologies, IT3, 2006, p. 202-216Conference paper (Refereed)
    Abstract [en]

    In this investigation, coal pellets were combusted using a high temperature oxidizer (600-1000°C), both in oxygen diluted and oxygen enriched conditions, using a small scale batch reactor able to preheat the oxidizer to 1000°C. The combustion process and flame are described and mass, temperature and heating rate as function of time for different oxidizer compositions and temperature discussed. The results show that high temperature conditions gives the highest mass loss rates. The influence of oxygen concentration on mass loss rate is more evidenced for enriched conditions and/or lower oxidizer temperatures. Diluted conditions are associated with large flames while a typical flame downstream from the sample was almost absent for oxygen concentrations above 50%. Ignition time is highly dependent on oxygen concentration only when a 600°C oxidizer was used while almost independent when a 1000°C oxidizer was used.

  • 125.
    Ponzio, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Senthoorselvan, Sivalingam
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzmierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Eriksson, Ola
    LKAB, Kiruna.
    Ignition of single coal particles in high-temperature oxidizers with various oxygen concentrations2008In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 87, no 6, p. 974-987Article in journal (Refereed)
    Abstract [en]

    In this investigation, coal pellets were combusted using a high temperature oxidizer with varying oxygen concentration, using a small scale batch reactor able to preheat the oxidizer to 1273 K. In base of the experimental results, the influence of oxygen concentration on the ignition mechanism, the solid temperature inside the particle at the moment of ignition, the mass lost at the moment of the ignition and ignition time is analyzed and discussed. A theoretical basis for the division of the conditions tested into three ignition regimes is developed and a formula for the prediction of the ignition time directly from the material and oxidizer temperature and oxygen concentration is proposed.

  • 126.
    Ponzio, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Combustion of solid fuels under the conditions of high temperature and various oxygen concentration2007In: Challenges on Power Engineering and Environment - Proceedings of the International Conference on Power Engineering 2007, ICOPE 2007 / [ed] Cen, K; Chi, Y; Wang, F, 2007, p. 871-876Conference paper (Refereed)
    Abstract [en]

    This work investigated the combustion phenomena of solid fuels, coal and wood pellets with use of high temperature oxidizers (873-1273 K), both in oxygen diluted and oxygen enriched conditions. The combustion process and flame are described and mass, temperature and heating rate as function of time for different oxidizer compositions and temperature are discussed. The results show that high temperature conditions give the highest mass loss rates. The influence of oxygen concentration on mass loss rate is more evidenced for enriched conditions and/or lower oxidizer temperatures. Diluted conditions are associated with large flames while a typical flame downstream from the sample was almost absent for oxygen concentrations above 50%. Ignition time is highly dependent on oxygen concentration only when a 873 K oxidizer was used while almost independent when a 1273 K oxidizer was used.

  • 127.
    Ponzio, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzmierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    A thermodynamic analysis of high temperature agent gasification (HTAG) using biomass and airIn: Clean Air, ISSN 1561-4417Article in journal (Other academic)
  • 128.
    Ponzio, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Lucas, Carlos
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzmierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Development of a thermally homogeneous gasifier system using high-temperature agents2006In: Clean Air, ISSN 1561-4417, Vol. 7, no 4, p. 363-379Article in journal (Refereed)
    Abstract [en]

    An advanced twin component gasification system, named Thermally Homogenous Gasification (THG), is developed. Development, testing and numerical simulations of the THG have shown that increased temperature of the gasification agent, results in a higher gasification rate, higher ignition front rate, higher molar fraction of combustible species in the product gas (CO, H2 and CmHn), and consequently a higher LHV. Moreover, there exists a critical gasification agent temperature above which preheating is no longer efficient if the purpose is to maximise the yield of gaseous products.

  • 129.
    Rafidi, Nabil
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Thermodynamic aspects and heat transfer characteristics of HiTAC furnaces with regenerators2005Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Oxygen-diluted Combustion (OdC) technology has evolved from the concept of Excess Enthalpy Combustion and is characterized by reactants of low oxygen concentration and high temperature. Recent advances in this technology have demonstrated significant energy savings, high and uniform thermal field, low pollution, and the possibility for downsizing the equipment for a range of furnace applications. Moreover, the technology has shown promise for wider applications in various processes and power industries.

    The objectives of this thesis are to analyze the thermodynamic aspects of this novel combustion technology and to quantify the enhancement in efficiency and heat transfer inside a furnace in order to explore the potentials for reduced thermodynamic irreversibility of a combustion process and reduced energy consumption in an industrial furnace. Therefore, theoretical and experimental investigations were carried out.

    The 2nd law of thermodynamics analyses of OdC systems have been carried out for cases in which the oxidizer is either oxygen (Flameless-oxy-fuel) or air (High Temperature Air Combustion, HiTAC). The analyses demonstrate the possibilities of reducing thermodynamic irreversibility of combustion by considering an oxygen-diluted combustion process that utilizes both gas- and/or heat-recirculation. Furthermore, the results showed that an oxygen-diluted combustion system that utilizes oxygen as an oxidizer, in place of air, results in higher 1st and 2nd law efficiencies.

    Mathematical models for heat regenerators were developed to be designing tools for maximized heat recovery. These models were verified by heat performance experiments carried out on various heat regenerators.

    Furthermore, experiments were performed in a semi-industrial test furnace. It was equipped with various regenerative burning systems to establish combustion and heat transfer conditions prevailing in an industrial furnace operating based on HiTAC. The tests were carried out at seven firing configurations, two conventional and five HiTAC configurations, for direct and indirect heating systems.

    Measurements of energy balance were performed on the test furnace at various configurations in order to obtain the 1st law efficiency. Moreover, local measurements of temperature, gas composition, and heat fluxes in the semi-industrial test furnace were performed to find out the main characteristics of HiTAC flame and the effects of these characteristics on the heating potential, i.e., useful heating in the furnace. In the case of HiTAC, these measurements showed uniformities of chemistry, temperature, temperature fluctuation, and heat fluxes profiles. The values of fluctuations in temperature were small. The high speed jets of the fuel and air penetrated deep into the furnace. The fuel gradually disappeared while intermediate species gradually appeared in relatively high concentrations and at broader regions inside the furnace. These findings indicate: a large reaction zone, low specific combustion intensity in the flame, low specific fuel energy release, and high heat release from this large flame. In addition to the thermodynamic limitations to the maximum temperature of the Oxygen-diluted Combustion, the low specific energy release of the fuel and the high heat release from the flame to its surroundings cause this uniform and relatively moderate temperature profile in a HiTAC flame, consequently suppressing thermal-NO formation.

    Heat flux and energy balance measurements showed that heating potential is significantly increased in the case of HiTAC compared to that in the conventional case, implying much more energy savings than the apparent heat recovery from the heat regenerators, and consequently much less pollutants emissions. Therefore, it is certain that this large HiTAC flame emits more thermal radiation to its surroundings than the conventional flame does, in spite of the moderate-uniform temperature profile of the flame. This intense heat flux was more uniform in all HiTAC configurations, including the indirect heating configuration, than that of the conventional-air combustion configuration.

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  • 130.
    Rafidi, Nabil
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Heat transfer characteristics of HiTAC heating furnace using regenerative burners2006In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 26, no 16, p. 2027-2034Article in journal (Refereed)
    Abstract [en]

    The aim is to experimentally study the various modes of heat transfer and to investigate the effect of the HiTAC flame characteristics on the heat transfer intensity and uniformity inside a setni-industrial test furnace using various industrial regenerative burners and various flame configurations namely; single-flame, twin-flame counter. twin-flame parallel and twin-flame stagger. Measurements of local instantaneous and average temperatures, heat fluxes and gas composition at several locations inside the furnace were carried out. It was observed that the HiTAC flame with highly reduced temperature fluctuations. turbulent intensity and combustion intensity have a larger reaction zone than a conventional flame. This large flame emits more thermal radiation in spite of its uniform and reduced temperature. Furthermore, the convective heat transfer was found to be uniform and as high as 30% of the total heat transfer to an object surface in the furnace. On the other hand, the very high reduction of NOx emission is a consequence of the low temperature and temperature fluctuation levels of the HiTAC flames. The above findings are valid to a similar extent in all burners and configurations but to less extent in the twin-flame counter configuration.

  • 131.
    Rafidi, Nabil
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Thermal performance analysis on a two composite material honeycomb heat regenerators used for HiTAC burners2005In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 25, no 17-18, p. 2966-2982Article in journal (Refereed)
    Abstract [en]

    Honeycomb heat regenerators do not only reduce the fuel consumption in a high temperature air combustion (HiTAC) burning system but also provide the necessary high temperature of combustion air. A two-dimensional simulation model was developed to numerically determine the dynamic temperature and velocity profiles of gases and solid heat-storing materials in a composite material honeycomb regenerator. Consequently, the energy storage and the pressure drop are calculated and the thermal performance of honeycomb heat regenerator is evaluated at different switching times and loading. The model takes into account the thermal conductivity parallel and perpendicular to flow direction of solid and flowing gases. It considers the variation of all thermal properties of solid material and gases with temperature, Moreover, the radiation from combustion flue gases to the storage materials was considered in the analysis, The results are presented in a non-dimensional form in order to be a design tool as well, These analyses were applied on a regenerator made of two layers of ceramic materials, one is pure alumina and other is cordierite. This regenerator is contained in a. 100 kW twin-type regenerative-burning system used for HiTAC. The effectiveness and the energy recovery rate were 88% and 72% respectively at nominal operating range of the regenerator and the pressure drop across the twin regenerator system wits 1.16 kPa. The periodic steady state condition is reached after about 11 min and it takes only 2 min of operation until the temperature of combustion air remains above the self-ignition temperature that is required for HiTAC. Furthermore. these mathematical analyses show good agreement with experiments made on the same regenerator. In the experiments, the dynamic behavior of the heat regenerator operation was considered in order to compensate measurement readings for this effect.

  • 132.
    Rafidi, Nabil
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Thermodynamic aspects of oxygen-deficient2005In: Archives of Thermodynamics, ISSN 1231-0956, Vol. 26, no 2, p. 29-44Article in journal (Refereed)
    Abstract [en]

    The oxygen deficient combustion (ODC) is characterized by reactants of low oxygen concentration and high temperature. This work is devoted to analysis of such combustion process from the thermodynamic point of view. It demonstrated the possibilities for reducing thermodynamic irreversibility of combustion by considering the oxygen-deficient combustion process that utilizes both gas- and heat-recirculation. Furthermore, an ODC system utilizes oxygen as oxidizer has higher 1st and 2nd low efficiencies compared to an ODC system using air as oxidizer. This study is a technical guidance for further efficiency-improvement in combustion process especially because the temperature increase due to the reaction in an ODC system is mild.

  • 133.
    Rafidi, Nabil
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology. Alstom Switzerland Ltd., Baden, Switzerland .
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Gupta, Ashwani K.
    High temperature air combustion (HITAC) phenomena and its thermodynamics2014In: ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 2014, Vol. 6AConference paper (Refereed)
    Abstract [en]

    The fundamentals and thermodynamic analysis of High Temperature Air Combustion (HiTAC) technology is presented with focus on industrial furnaces as they are amongst the major energy users. The HiTAC is characterized by high temperature of combustion air having low oxygen concentration. This study provides a theoretical analysis of HiTAC a process from the thermodynamic point of view. The results demonstrate the possibilities of reducing thermodynamic irreversibility of combustion by considering an oxygen-deficient combustion process that utilizes both gas- and heat-recirculation. Furthermore, combustion with the use of oxygen (in place of air) is also analyzed. The results showed that a system which utilizes oxygen as an oxidizer results in higher 1st and 2nd law efficiencies as compared to the case with air as the oxidizer. This study is aimed at providing technical guidance to further improve efficiency of a combustion process which show very small temperature increases due to mild chemical reactions. The significant of these findings are now widely used in industrial furnaces with singular successes on energy savings, pollution reduction and reduced size of the equipment. The exergy analysis too can be used as a technical tool to improve efficiency in combustion processes.

  • 134.
    Rafidi, Nabil
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Gupta, Ashwani K.
    High-temperature air combustion phenomena and its thermodynamics2008In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 130, no 2, p. 023001-Article in journal (Refereed)
    Abstract [en]

    The fundamentals and thermodynamic analysis of high-temperature air combustion (HiTAC) technology is presented. The HiTAC is characterized by high temperature of combustion air having low oxygen concentration. This study provides a theoretical analysis of HiTA C process from the thermodynamic point of view. The results demonstrate the possibilities of reducing thermodynamic irreversibility of combustion by considering an oxygen-deficient combustion process that utilizes both gas and heat recirculations. HiTA C conditions reduce irreversibility. Furthermore, combustion with the use of oxygen (in place of air) is also analyzed. The results showed that a system, which utilizes oxygen as an oxidizer results in higher first and second law efficiencies as compared to the case with air as the oxidizer. The entropy generation for an adiabatic combustion process is reduced by more than 60% due to the effect of either preheating or oxygen enrichment. This study is aimed at providing technical guidance to further improve efficiency of a combustion process, which shows very small temperature increases due to mild chemical reactions.

  • 135.
    Rafidi, Nabil
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Jewartowaski, Marcin
    Szewczyk, Dariusz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Increase of the Effective Energy from the Radiant Tube Equipped with Regenerative System in Comparison with Conventional Recuperative System2005In: IFRF Combustion Journal, ISSN 1562-479X, no 03, p. 1-17Article in journal (Refereed)
    Abstract [en]

    This paper presents the experimental results of High Temperature Air Combustion (HiTAC)investigations with the use of a radiant tube, in order to compare the Regenerative System (RS)with a conventional recuperative system.For this work a semi-industrial HiTAC test furnace was equipped with the W-shape RadiantTube. The working length of this tube was around 7,0 m and the diameter was 0,195 m. Theradiant tube was operated in sequence with a conventional recuperative system and aRegenerative System. The recuperative burner was mounted in the upper end of the tube. TheRS consisted of two burners, equipped with honeycomb ceramic regenerators, mounted to bothends of the radiant tube. The temperature profile of the tube wall was monitored by 74thermocouples located along the tube. Additional temperatures, flow rates and pressures weremeasured to assess and compare the energy balance of both systems. Pollutant emissions,including NOx and CO, as well as the exhaust gas composition were measured. The tests werecarried out over a wide range of parameters: firing power from 75 kW to 155 kW, furnacetemperature from 670°C to 950°C and an oxygen molar fraction in the exhaust gases set at 3%.LPG was used as a fuel in all tests.Test results show that the temperature profiles along the tube were more uniform when theregenerative system was used. The cross-sectional temperature distribution for the tube wasalso more uniform. Because of the relatively flat temperature distribution along the tube, moreenergy from the radiant tube can be emitted using RS in comparison with the conventionalrecuperative burner, for the same maximum temperatures of the tube. In certain conditions, theincrease of energy release can be up to 100%.Energy balance calculations show that the efficiency of the Regenerative System can be up to25% higher than that of the recuperative system, mainly due to very low temperature of fluegases for RS operation. Although, the preheated air temperature used for combustion wasmuch higher in the case of the regenerative system (in some tests as high as 960°C), the NOxemission was found to be almost the same in both cases.

  • 136.
    Rafidi, Nabil
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Włodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Thermodynamic aspects of oxygen-deficient combustion2005In: Archives of Thermodynamics, ISSN 1231-0956, E-ISSN 2083-6023, Vol. 26, no 2, p. 29-44Article in journal (Refereed)
    Abstract [en]

    The oxygen deficient combustion (ODC) is characterized by reactants of low oxygen concentration and high temperature. This work is devoted to analysis of such combustion process from the thermodynamic point of view. It demonstrated the possibilities for reducing thermodynamic irreversibility of combustion by considering the oxygen-deficient combustion process that utilizes both gas- and heat-recirculation. Furthermore, an ODC system utilizes oxygen as oxidizer has higher 1st and 2nd low efficiencies compared to an ODC system using air as oxidizer. This study is a technical guidance for further efficiency-improvement in combustion process especially because the temperature increase due to the reaction in an ODC system is mild.

  • 137.
    Ratnasari, Devy Kartika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Two-stage ex-situ catalytic pyrolysis of lignocellulose for the production of gasoline-range chemicals2018In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 134, p. 454-464Article in journal (Refereed)
    Abstract [en]

    The appropriate system is needed to produce a scalable and economically viable renewable energy from biomass. The objective of this study is to improve the quality of bio-oil, in terms of Organic Liquid Product (OLP), water content, acidity, favourable fractions, as well as gasoline-range chemicals. The influence of a staged layered catalyst system consists of a mesoporous catalyst, Al-MCM-41, and a microporous catalyst, HZSM-5, on the bio-oil quality was investigated. Additionally, the effect of reaction temperatures in the range of 400-600 degrees C with the optimum staged catalyst system on the catalytic pyrolysis product was analysed. The experiments of lignocellulosic biomass pyrolysis and catalytic pyrolysis were performed using a fixed bed reactor equipped with oil condensers and a gas collection sample bag. The quality of bio-oil produced from the thermal pyrolysis of lignocellulosic biomass, catalytic pyrolysis with single catalysts, catalytic pyrolysis with the staged catalyst system, as well as catalytic pyrolysis with mixed catalyst system was studied. The results show that Al-MCM-41 with HZSM-5 in the staged catalyst system enhanced the production of favourable compounds: hydrocarbons, phenols, furans, and alcohols. The favourable compounds yield that boosted 5.25-6.43% of that with single HZSM-5 catalyst was produced with HZSM-5:Al-MCM-41 mass ratio of 3:1 and 7:1. The pyrolysis and catalysis temperature of 500 degrees C with HZSM-5:Al-MCM-41 ratio of 3:1 obtained the optimum quality of bio-oil with 11.08 wt.% of OLP, 76.20% of favourable fractions, 41.97 wt.% of water content, low TAN of 43.01 mg-KOH/g, high deoxygenation, as well as high gasoline-range production of 97.89%.

  • 138.
    Sadat, Elaheh Sadat
    et al.
    Amirkabir Univ Technol, Elect Engn Dept, Tehran 158754413, Iran.
    Faez, Karim
    Amirkabir Univ Technol, Elect Engn Dept, Tehran 158754413, Iran.
    Saffari Pour, Mohsen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. Sharif Univ Technol, Dept Mech Engn, Tehran 1458889694, Iran.
    Entropy-Based Video Steganalysis of Motion Vectors2018In: Entropy, ISSN 1099-4300, E-ISSN 1099-4300, Vol. 20, no 4, article id 244Article in journal (Refereed)
    Abstract [en]

    In this paper, a new method is proposed for motion vector steganalysis using the entropy value and its combination with the features of the optimized motion vector. In this method, the entropy of blocks is calculated to determine their texture and the precision of their motion vectors. Then, by using a fuzzy cluster, the blocks are clustered into the blocks with high and low texture, while the membership function of each block to a high texture class indicates the texture of that block. These membership functions are used to weight the effective features that are extracted by reconstructing the motion estimation equations. Characteristics of the results indicate that the use of entropy and the irregularity of each block increases the precision of the final video classification into cover and stego classes.

  • 139.
    Saffari Pour, Mohsen
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Performance of pulverized coal combustion under high temperature air diluted by steam2014In: ISRN Mechanical Engineering, ISSN 2090-5122, E-ISSN 2090-5130, Vol. 2014Article in journal (Refereed)
    Abstract [en]

    The high temperature air combustion (HiTAC) is an advanced promising technology for heat recovery, energy saving, and stability improvement of flame. Computational fluid dynamic (CFD) is known as an applied tool to execute HiTAC modeling. In this paper, performances of pulverized coal combustion under the high preheated and oxygen deficient air are studied by both experimental and numerical methodology. The experimental facilities have been accomplished in a HiTAC chamber with coal injection velocity that ranges from 10 to 40 m/s. In order to achieve different preheated temperatures, the combustion air in such system is diluted by variable steam percentages from 0 to 44%. Results of mathematical simulation and experimental tests present convincible agreement through whole region. It is concluded that NOX emission is reduced by increasing the steam percentage in the oxidizer due to decreasing the flame temperature. Besides, graphical contours show that by adding more steam to oxidizer composition, the oxygen concentration decreased. Additionally, results show that when the injection speed of fuel is increased, NOX emission is also increased, and when the injection rate of preheated air is increased, NOX emission shows decreasing trend. Further contribution in future is needed to investigate the performance of such technologies.

  • 140.
    Said, Mahir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Mellin, Pelle
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Zhang, Qinglin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Liu, Hao
    State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology.
    Weihong, Yang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Litteraturstudie avseende förnybara bränslen för stålindustrin2013Report (Other academic)
  • 141.
    Salem, A. M.
    et al.
    Mechanical Power Department, Faculty of Engineering, Tanta University, Egypt. Systems, Power and Energy Research Division, James Watt School of Engineering, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.
    Zaini, Ilman Nuran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Paul, M. C.
    Systems, Power and Energy Research Division, James Watt School of Engineering, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The evolution and formation of tar species in a downdraft gasifier: Numerical modelling and experimental validation2019In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 130, article id 105377Article in journal (Refereed)
    Abstract [en]

    Gasification is one of the most important methods for converting biomass to syngas currently used in energy production. However, tar content in syngas limits its direct use and thus requires additional removal techniques. The modelling of tar formation, conversion and destruction along a gasifier could give a wider understanding of the process and subsequently help in tar elimination and reduction. However, tar complexity, which contains hundreds of species, makes the modelling process hard and computationally intensive, because the chemistry of the formation and the combustion of many species have not yet been fully studied. In this work, a detailed kinetic model for the evolution and formation of tar from downdraft gasifiers, for the first-time, was built. The model incorporates four main tar species (benzene, naphthalene, toluene, and phenol) with a total of eighteen different kinetic reactions implemented in the code for every zone. Experimental work was carried out to initially validate the results of the kinetic code and found a good agreement. Further experiments were conducted at three different equivalence ratios (ERs) and at three different temperatures (800, 900, and 1100 °C). Sensitivity analysis was then carried out by the kinetic code to optimise the working parameters of a downdraft gasifier that led to a higher calorific value of syngas. The results reveal that a tar evolution model is more accurate for wood biomass materials and that using ER around 0.3, and moisture content levels lower than 10% lead to the production of higher value syngas with lower tar amounts.

  • 142. Skoulou, V.
    et al.
    Kantarelis, E.
    Arvelakis, S.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Zabaniotou, A.
    Effect of biomass leaching on H-2 production, ash and tar behavior during high temperature steam gasification (HTSG) process2009In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 34, no 14, p. 5666-5673Article in journal (Refereed)
    Abstract [en]

    The effect of biomass water leaching on H-2 production, as well as, prediction of ash thermal behavior and formation of biomass tar during high temperature steam gasification (HTSG) of olive kernel is the main aim of the present work. Within this study raw olive kernel samples (OK1, OK2) and a pre-treated one by water leaching (LOK2) were examined with regard to their ash fouling propensity and tar concentration in the gaseous phase. Two temperatures (T = 850 and 950 degrees C) and a constant steam to biomass ratio (S/B = 1.28) were chosen in order to perform the steam gasification experiments. Results indicated that considering the samples' ash thermal behavior, it seemed that water leaching improved the fusibility behavior of olive kernel; however, it proved that water leaching does not favour tar steam reforming, while at the same time decreases the H-2 yield in gas product under air gasification conditions, due to possible loss of the catalytic effect of ash with water leaching.

  • 143. Skoulou, V.
    et al.
    Swiderski, Artur
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Zabaniotou, A.
    Process characteristics and products of olive kernel high temperature steam gasification (HTSG)2009In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 100, no 8, p. 2444-2451Article in journal (Refereed)
    Abstract [en]

    Exploitation of olive kernel for bioenergy production, with respect to the green house gases (GHGs) mitigation, is the main aim of this work. In this study, olive kernels were used as a solid biofuel, and high temperature steam gasification (HTSG) was investigated, in the fixed bed unit at KTH Sweden, with regard to hydrogen maximization in the produced gasification gas. Experiments were carried out in a temperature range of 750-1050 degrees C, with steam as the gasifying agent. The behaviour of olive kernels, under residence times from 120 up to 960 s, has been studied. At 1050 degrees C, a medium to high calorific value gas was obtained (LHVgas = 13.62 MJ/Nm(3)). while an acquired H-2/CO molar ratio equal to four proved that olive kernel HTSG gasification could be an effective technology for a hydrogen-rich gas production (similar to 40%vv H-2 in the produced gasification gas at 1050 degrees C). The produced char contained 79%ww of fixed carbon, low chlorine and sulphur content, which enables it for further re-use for energetic purposes. Tar content in the produced gas at 750 degrees C was 124.07 g/Nm(3), while a 1050 degrees C at 79.64% reduction was observed and reached the value of 25.26 g/Nm(3).

  • 144. Stasiek, J.
    et al.
    Jewartowski, M.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Small Scale Gasification of Biomass and Municipal Wastes for Heat and Electricity Production using HTAG Technology2017In: E3S Web of Conferences, EDP Sciences, 2017, Vol. 13, article id 03005Conference paper (Refereed)
    Abstract [en]

    Combustion and gasification technology utilizing high-cycle regenerative air/steam preheater has drawn increased attention in many application areas. The process is to be realized at temperature level above ash melting point using highly preheated agent. The use of highly preheated media above 900°C provides additional energy to conversion processes and results in considerable changes to the design of combustion and gasification equipment and its performance. This paper presents an advanced gasification system that utilizes high-temperature air and steam to convert biomass and municipal wastes into syngas production as well as selected results from experimental studies of high temperature air/steam gasification.

  • 145.
    Sun, Yunjuan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Jiang, Jianchun
    Kantarelis, Efthymios
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Xu, Junming
    Li, Linna
    Zhao, Shuheng
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Development of a bimetallic dolomite based tar cracking catalyst2012In: Catalysis communications, ISSN 1566-7367, E-ISSN 1873-3905, Vol. 20, p. 36-40Article in journal (Refereed)
    Abstract [en]

    In this study a bimetallic dolomite based tar cracking catalyst was developed and tested. It was enriched in Ni and Fe with BET surface area of 12.31 m(2)/g. The catalytic characterizations were tested with tar simulated by naphthalene, and with tar produced by biomass and coal co-pyrolysis. 93% naphthalene was decomposed at 950 degrees C. A first order apparent kinetic model was developed. Activation energy of 63.96 kJ/mol and pre-exponential factor of 396.2/s were calculated. Furthermore, reduction in char yield by 7%, when the catalyst was used in the biomass-coal co-pyrolysis, was observed.

  • 146. Sundqvist, M.
    et al.
    Mellin, Pelle
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Salman, H.
    Hultgren, A.
    Nilsson, L.
    Wang, C.
    System analysis of integrating fast pyrolysis to an iron and steel plant2015In: ECOS 2015 - 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, International Conference on Efficiency,Cost, Optimization, Simulation and Environmental Impact of Energy Systems , 2015Conference paper (Refereed)
    Abstract [en]

    The reducing of CO2 allowance promotes steel industry to mitigate CO2 emissions. Utilization of biomass e.g., as injectants in the blast furnace to replace pulverized coal (PC), has been proposed as one promising option to meet these requirements in the short- Term. The aim of this work is to integrate a biomass fast pyrolysis to the iron and steel industry and to investigate the potential effects on the energy consumption and CO2 emission. In this work, an iron and steel plant from Sweden was chosen as a case study. An optimization model was extended to cover the fast pyrolysis units in the system boundary. The fast pyrolysis plant produces different types of biomass products i.e., bio-char, bio-oil and bio-syngas. Different alternative to utilize biomass products within the system were included in the model. The investigation shows that the integration of a fast pyrolysis units has great potential on, not only reducing CO2 emission, the potential energy savings.

  • 147.
    Surroop, Dinesh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology. University of Mauritius, Faculty of Engineering, Chemical and Environment Engineering, Mauritius .
    Mohee, R.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Włodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Waste to energy: A source of energy to reduce greenhouse gas in mauritius2008In: Air and Waste Management Association, 2008, p. 755-765Conference paper (Refereed)
    Abstract [en]

    Energy is one of the most basic of human needs and is extremely crucial for continued human development. The global demand for energy is rapidly increasing with increasing human population, urbanization and modernization. The growth in global energy demand is projected to rise sharply over the coming years. The enormous amount of energy being consumed across the world is having adverse implications on the ecosystem of the planet. The world heavily relies on fossil fuels to meet its energy requirements. Fossil fuels are inflicting enormous impacts on the environment. Climatic changes driven by human activities, in particular the production of greenhouse gas emissions (GHG), directly impact on the environment. Municipal Solid Waste (MSW) is regarded as biomass; therefore almost all the carbon dioxide generation from the combustion system should be carbon neutral. Since there are around 1200 tons of MSW generated daily in Mauritius, this can be a good source of energy. The study was, therefore, initiated to assess the amount of GHG being avoided by using MSW as a source of energy. The results showed that that the amount of energy per unit weight that is generated from MSW was 1.85 kWh/kg. The amount of GHG emitted from combustion of MSW was 0.153 kg CO 2/kg MSW. The amount of GHG per unit of electricity generated by the combustion of MSW was 250 g CO 2/ kWh e. It was found that 640 g CO 2/kWh e by replacing coal by MSW and 470 g CO 2/kWh e can be avoided by replacing oil by MSW.

  • 148.
    Svanberg, Rikard
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Ex-situ Ion Enhanced Pyrolysis of Biomass: Effects of low power high voltage spark on the pyrolysis products2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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  • 149.
    Tsamba, Alberto J.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Włodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Cashew nut shells char reactivity and combustion kinetics2007In: A and WM, Annual International Conference on Incineration and Thermal Treatment Technologies, IT3, 2007Conference paper (Refereed)
    Abstract [en]

    Combustion process is regarded as the most primitive and well-known chemical reaction. However, as the research on combustion increases, it becomes a fact that it is a very complex process with different parameters and features that cannot be studied at the same time and therefore, are not well known as such. In this study, cashew nut char, produced through pyrolysis at three different heating rates, is submitted to a combustion using a binary mixture of O 2 and He to study char reactivity and determine char combustion kinetic parameters. Reactivity is studied by using the critical temperature approach and peak separation software while kinetics is determined through the NETZSCH advanced software that allows the determination of the frequency factor, the activation energy and the reaction order. The results are compared to the similar data available from the literature for other biomasses. Cashew nut shells pyrolysis char was found to be more reactive than char from olive husks, grape residues and pine woods pyrolysis.

  • 150.
    Tsamba, Alberto Júlio
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Fundamental Study of two Selected Tropical Biomasses for Energy: coconut and cashew nut shells2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

     Cashew nut and coconut shells are two potential renewable and environmentally friendly energy sources that are commonly found as agro-industrial wastes in tropical countries. Despite this fact, they are not yet widely studied as such. Given this lack of specific technical and reliable data, technologies for their conversion into energy cannot be designed with confidence as it happens with other commonly studied biomass feedstock. Thus, the need to generate these data guided this research in order to provide technical information for the designing of appropriate thermochemical conversion technologies for energy generation, particularly, in remote areas, where electricity grid is neither a feasible nor an affordable solution.Among thermochemical processes, pyrolysis plays a key role as it is found in both combustion and gasification at their earlier stages. In both technologies, pyrolysis products are generated and later submitted to further transformations according to the process in use.Hence, pyrolysis was selected for thermal characterisation of cashew nut and coconut shells. The main characteristics envisaged are i) pyrolysis profiles; ii) global, semi-global and individual kinetics; iii) pyrolysis global and individual yields; iv) modelled pyrolysis yields at high heating rates; and, v)char combustion kinetics and reactivity. The main technique used for experimental data generation is thermogravimetry and FTIR spectroscopy. Data experimentally generated from TG and TG-FTIR experiments were processed through different methods and codes, such as the Coats and Redfern model-fitting method, the modelfree methods of Ozawa-Flynn-Wall, Friedman and ASTM E698, for semi-global and global kinetics; DAEM and FG-Biomass were used for pyrolysis individual kinetics and yields determination. Proximate and ultimate analyses were performed as well.The study revealed peculiar characteristics compared to the commonly known lignocellulosic biomass. The volatiles content was above 66%w/w; hemicelluloses DTG peak did not overlap with the cellulose peak; the global pyrolysis activation energies were around 200 and 120 kJ/mol for coconut and cashew nut shells, respectively. Hemicelluloses and cellulose showed varying activation energies as 130-216 and 155-208 kJ/mol, respectively. Char combustion showed two steps with activation energies of 135 and 121 kJ/mol (cashew nut shells); 105 and 190kJ/mol (coconut shells). Individual yields and kinetics were determined for 17 compounds, including tars. These data are of key importance for modelling and the consequent data generation for the designing of appropriate thermochemical energy for these biomasses.

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